Write-Up: Replacing Belts and Pulleys

AA wrote:

Quote :

Are the pulleys known to go bad in this engine?

Yes, starting about 85k miles, you can expect them to go one by one. In my case, I got about 150 miles out of each one after they started making noise, which was more like a grinding/chuffing sound at low RPM.

If you wait until they fail, you will probably need to replace the serpentine belt(s) as well, unless you can stop the car immediately. If you notice any of the following, turn the key off and coast to the side of the road immediately, inspect under hood:

• significant loss of power (no supercharger sound)
• steering becomes very hard (power steering loss)
• sudden high coolant temp (no water pump)
• quiet "thump" under the hood (belt has slipped off)
• repeating "tap-tap-tap" sound (part of belt slapping hood)

If you can pull over within 10 secs of the event, could save you the price of a belt(s), and the time of going through belt replacement(s).

I haven't gotten to the point of it making much noise at all. It's more of a whining scraping noise that's been going on for the last 10,000 miles that I've owned the car (I hate putting so many miles on her). Mainly noticeable at startup until warm or when you have the hood opened and standing by the belt.

How many pulleys are there that need to be replaced? Do you do the one on the power steering, supercharger, ac compressor, alternator and the other accessories that I forgot to mention too, or just the guide pulleys?

I've had my fair share of serpentine belt failures on my last car. The water pump literally fell apart once, and the last time it was the alternator that completely seized shredding the belt. Believe it or not it was the original alternator with over 250,000 miles on it at the time. I was shocked.

Mainly it's the idle and tensioner pulleys. We just have so many. I've had 3 fail - the SC idler, one inside the motor mount, and accessory tensioner pulley.

When the noise starts occurring unevenly in spurts, it's time to get it taken care of.

I just did belts and pulleys. The car runs fine, but it's got a loud whine coming from the pulley area. Ugh! Using a piece of heater hose to my ear, it sounds like the lower SC idler, 89006- you know the one right behind the bracket! And it's a brand new pulley! I sold DeMONTE my black Riv so I could get this low mileage one (51kmi). I think this car is haunted, always has a problem. The black one I sold ran flawless!

It could be that when you replaced the lower pulley, it didn't seat all the way on the post, so now is touching the bracket? Take a good close look at it. Remove the belt and spin the pulleys by hand.

I'll try that Derek. I hope you're right!

GMFreak8 wrote:

How many pulleys are there that need to be replaced?

Go to pg 1?

Jack the R wrote:

GMFreak8 wrote:

How many pulleys are there that need to be replaced?

Go to pg 1?

Hey some of these posts are before my fifth cup of coffee. It makes it hard for me to comprehend things then.

71gsx455-4spd wrote:

I just did belts and pulleys. The car runs fine, but it's got a loud whine coming from the pulley area. Ugh! Using a piece of heater hose to my ear, it sounds like the lower SC idler, 89006- you know the one right behind the bracket! And it's a brand new pulley! I sold DeMONTE my black Riv so I could get this low mileage one (51kmi). I think this car is haunted, always has a problem. The black one I sold ran flawless!

Sorry to hear Ken!!! If you want, I can stop over and give you a hand with it. I just started getting an odd harmonic howling sound from the black Riv and decided to change out all the tensioners and idlers I could get at easily. I'll wait to do that dreaded idler in the engine bracket. Give me a holler if you want, I've got some free time in the next couple days. I also have a spare idler that you can try if you have the car apart.

Edit: I'll take that car off your hands if you're sick of it!!! J/K

I'm not sure where to find the pulleys as far as purchasing. So you're telling me there are four pulleys, not five? Unless you include the supercharger?

All I see for parts is this:

Tensioner Pulleys -

Gates # 38015

Gates #38006

Gates #38009

7505118
#12564510
GR.1.062 _____ I had to get the lower SC idler pulley from a dealer.
These are the #'s I found on the box.

What is the last one trying to say? Are these parts simply available from the dealer or from autozone or whatever? I'm just trying to understand things here, not trying to be lazy.

I think you will find that www.rockauto.com works well. I usually look up suggested part numbers from write-ups there, as it has a great online cross reference to other part numbers for the same part. Then you can order from them, or a random parts place like autozone, partsource, napa etc...

example: head to rockauto.com, click on the big red catalogue button, select 1998, buick, riviera, supercharged, and belt drive. There are your pulleys

GMFreak8 wrote:

I'm not sure where to find the pulleys as far as purchasing. So you're telling me there are four pulleys, not five? Unless you include the supercharger?

Technically everything has a pulley, but here we're only talking about the idler pulleys. So yes, there are only 4, 3 easy ones and one horror. And I admit, sometimes a person may say "tensioner pulley" to further narrow it down, but the pulleys mounted to the tensioner arms are basically the same kind as the stationary idlers...

Karma is right about RockAuto and other places. Plus, other manufacturers may also make steel replacements for pulleys that were originally plastic. I'm not sure that we ever reached a consensus on here about that, as the bearings probably fail more than the pulley material itself... Personally, I know one of my original plastic pulleys got replaced with a metal one.

I prefer the metal pulleys to plastic myself but if a pulley bearing goes, it probably doesn't matter what material the pulley is made of.

You are looking to replace three total for the SC drive and one for the accessory drive. When you are looking under the hood, the supercharger will have a grooved idler closest to the front of the bay followed by a smooth pulley (tensioner) right behind that. You'll see the horror idler pulley sitting right in the engine bracket a little lower in the bay. It's bigger than the other two pulleys and it is smooth. Finally, the accessory drive tensioner is a smooth pulley sitting near the alternator. There's good images of all these pulleys early on in this thread.

I've used both metal and plastic pulley replacements. They both work fine, as it's the bearing in the pulley that's most important - that's the part that normally fails. Both steel and plastic have their advantages:

Steel:

• may work as a heat sink to draw heat away from the bearing. This could permit a failing pulley to last a little longer than a plastic one (which will melt).

• more durable if you are under the hood a lot. Bumping or dropping a steel pulley will probably not damage it.

Plastic:

• lighter than steel, so less parasitic loss. This is a small gain, but a gain.

• less expensive than steel.

I use plastic for the grooved pulleys, steel for smooth. If a pulley starts making noise, I replace it. Have never seen either plastic or steel pulleys fail from anything other than a bad bearing.

So there is no need to replace the power steering pulley. We simply need to replace the pulleys associated with the supercharger belt and then the accessory drive? I went to rockauto and there's like 10 different pulleys and not much description. Maybe I'm being thickheaded, but this is confusing the hell out of me.

EDIT:

WAIT!! I finally get it. Jesus I feel like one total dumbass. OK. Now I just have to find the parts and I'll be all set. I REALLY REALLY appreciate all the patience guys and not yelling at me.

I was researching pulleys online for cheapest prices, and I came across GATES # 38001 for the fourth pulley that that is the lower supercharger idler pulley. Rockauto has it for $15 and some change. Does it look like the pulley that is needed that AA could only find through the dealer?

Tensioner Pulleys -

Gates # 38015

Gates #38006

Gates #38009

Gates #38001

All those all the pulleys I need?

We're all pretty much agreed on the bearings being the main failure point, but I was reading an older thread by 1998 Riv and I remembered why at least one of mine is metal. The grooved pulleys don't seem to have any trouble in plastic, unless something gets in there and chips them. However, the life of the smooth plastic pulleys may not be as good as the steel ones, nor may they be as perfectly flat as steel... In fact, I think one of the pulleys on our '92 LeSabre had to be replaced at quite low mileage because the surface became uneven.

We're also not talking about a helluva lot of money no matter what you buy. If I thought I'd never have to touch it again, I'd pay 3 times as much for an unobtanium replacement for that miserable lower SC pulley... In the final analysis, I would recommend going ahead with the Gates plastic ribbed pulleys, but buying the Dayco (or whoever) metal pulleys for the smooth ones.

(Don't forget to reference that Belt & Pulley Write-up as you go along, especially about which pulley-bolts are reverse-thread!)
.

I've never seen a smooth plastic pulley. I thought the smooth ones were all steel. I agree, the steel ones should be stronger.

As odd as this may sound, I believe both smooth pullies on my SC assembly were plastic (tensioner as well as 3.5" bitch idler). They both had a really interesting indentation worn in them from the belt path. I replaced both with metal pullies but the grooved idler was a plastic one (from NAPA).

edit: Kyle

If I were you, I'd grab the following:

SC
Dayco 89006 (3.5" bitch idler METAL)
Dayco 89007 (3.0" tensioner METAL)
Dayco 89051 (3.0" grooved tensioner METAL) OR Gates 38009 (3.0" plastic)

Accessory Drive
Dayco 89007 (3.0" tensioner METAL)

NOTE: both tensioner pullies are the same part #. they are nothing different.

No worries on the questions. If you're really new at this stuff, it can seem confusing having two belt drives to deal with.

AA wrote:

I've never seen a smooth plastic pulley. I thought the smooth ones were all steel. I agree, the steel ones should be stronger.

This is the Gates/Delco 38015...

Interesting. When mine fragged, the Buick dealership replaced it with a stock steel part.

AA wrote:

Interesting. When mine fragged, the Buick dealership replaced it with a stock steel part.

Mine too, sort of. The dealer replaced it with a steel one but would not give me the P/N. One mechanic told me it was off a Ford Thunderbird but was right size etc. Another said they took it off a Bonneville. I ran it for some years; I just took it off some months ago when I replaced the entire tensioner assembly.

Thinking out loud - the plastic pulley ought to be fine for this application, BUT when it starts squeaking you better replace it quick otherwise the bearing will heat the pulley up and it will grenade on you all of a sudden. The steel one can't grenade. What mine did when it wore was it started running cocked on its axis. I imagine the SC would have eventually thrown the belt.

Albertj

I once had a plastic SC idler pulley fail - the pulley did not fragment, but the bearing did. The plastic ring stayed aligned with the belt, spinning around the idler bolt long enough for me to pull over and swap out a spare (yep, I keep spare pulleys and a ratchet in the trunk!).

PS - when you remove the hood insulation, you can better hear when problems like this develop.

DEMonte1997 wrote:

As odd as this may sound, I believe both smooth pullies on my SC assembly were plastic (tensioner as well as 3.5" bitch idler). They both had a really interesting indentation worn in them from the belt path. I replaced both with metal pullies but the grooved idler was a plastic one (from NAPA).

edit: Kyle

If I were you, I'd grab the following:

SC
Dayco 89006 (3.5" bitch idler METAL)
Dayco 89007 (3.0" tensioner METAL)
Dayco 89051 (3.0" grooved tensioner METAL) OR Gates 38009 (3.0" plastic)

Accessory Drive
Dayco 89007 (3.0" tensioner METAL)

NOTE: both tensioner pullies are the same part #. they are nothing different.

No worries on the questions. If you're really new at this stuff, it can seem confusing having two belt drives to deal with.

Awesome!! Thanks for the part numbers!!! +one

I'll be picking those up.

is there a trick to doing this idler pully for the supercharger in front of the motor mount....or how do you know how to do it the easiest way???...i have a 98 riv sc

thanks

billythekid7 wrote:

is there a trick to doing this idler pully for the supercharger in front of the motor mount....or how do you know how to do it the easiest way???...i have a 98 riv sc

thanks

Trick?

what's the problem?

Please note that some of the pullies are on bolts that are reverse threaded. Easy to tell which is which, the belt always runs in the direction you have to turn the bolt to tighten it. So to take the pulley off, have to turn that bolt the other way.

Albertj

albertj wrote:

billythekid7 wrote:

is there a trick to doing this idler pully for the supercharger in front of the motor mount....or how do you know how to do it the easiest way???...i have a 98 riv sc

thanks

Trick?

what's the problem?

Please note that some of the pullies are on bolts that are reverse threaded. Easy to tell which is which, the belt always runs in the direction you have to turn the bolt to tighten it. So to take the pulley off, have to turn that bolt the other way.

Albertj

The "problem" is that you need to support the motor, and remove the front motor mount bracket from the engine. There's no easy way to do this - the bracket has to come off. I recall having to remove the engine mount bolt, and maybe the mount, lowering the engine so the bottom stud would clear the frame, then the other two studs were easy enough to remove. While the bracket is off, it will facilitate easier future belt changes if you cut the bottom 2" spacer in half - then in the future you can remove the spacer without having to drop the motor to pull that lower stud.